Thanks for this explanation. Definitely helped me understand more about your design decisions. I agree with the mana costing presented here. It makes sense. Changing votes within the same "spectrum" shouldn't really cost anything; like decreasing positive numbers or increasing negative numbers.
Comments can specify up to 5 SMTs that can vote on them, for a total of 6 assets (5 SMTs plus STEEM).
This will enable content to participate in multiple economies. Powerful capability.